/Engine/Source/Runtime/Engine/Classes/Engine/LevelStreaming.h
Sets loaded level, fixups for PIE, notifies level is loaded, apply necessary modifications on level once loaded.
void PrepareLoadedLevel ( [ULevel](API\Runtime\Engine\Engine\ULevel) * InLevel, [UPackage](API\Runtime\CoreUObject\UObject\UPackage) * InLevelPackage, int32 InPIEInstanceID )